MIAMI - West Nile virus may be three times more deadly than previously thought, because many deaths associated with the mosquito-borne virus occur years after the initial infection, researchers have said. The findings were based on a study of 4,144 people in Texas, and were presented at the 2016 Meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in Atlanta, Georgia. Among this group of people who became ill with West Nile virus between 2002 and 2012, 286 people died in the first three months.